1. Field of the Invention
This invention relates generally to modeling language for 3D graphics and, more particularly, to temporal manipulation of media assets.
2. Description of the Related Prior Art
Conventional modeling languages for real-time 3D scene rendering have traditionally focussed on aspects of scene structure, geometry, appearance, and, to some degree, animation, and interactivity. This focus has been driven by the following two factors. First, 3D computer graphics applications have been geared toward user-driven experiences and, thus, tend to be structured around a rendered response to events. Second, the majority of these applications take a xe2x80x9crender it as fast as you canxe2x80x9d approach to scene updates, with little respect paid to fidelity of the time base. Conventional modeling languages fail to provide the accuracy of temporal relationship between two media assets. For example, if a video asset and an audio asset are to start at the same time, this can be achieved by prescribing start time for each asset independent of other assets. This allows the start times to be slightly different. It is desirable that the start time for each asset be controlled by the same field, thereby resulting in accurate synchronization of the assets. Media assets include audio media, video media, animations, audio-visual media, images or events.
As full motion video and high fidelity audio are integrated into a scene rendering mix, it is desirable to deliver high quality television-like viewing experiences while supporting viewer interactivity. It is desirable to provide a passive viewing experience that is more television-like and not a web page-like viewing experience.
In a declarative markup language, the semantics required to attain the desired outcome are implicit in the description of the outcome. It is not necessary to provide a separate procedure (i.e., write a script) to get the desired outcome. One example of a declarative language is HyperText Markup Language (HTML).
Various approaches to scoring animation and playback have previously been developed in other computer-based media, including Macromedia Director and the W3C""s Synchronized Multimedia Integration Language (SMIL). However, these existing scoring systems do not allow for declarative composition of a real-time scene wherein the independent scores are dynamically composed and decomposed hierarchically, structuring time in manner akin to the spatial scene graph. For example structuring blocks of time to be next to each other or structuring block of time to be parallel (synchronized) with each other. The conventional scoring systems do not allow variable rate and direction of score evaluation to be done declaratively, and neither do they allow declarative implementation of a modular computation strategy based upon a normalized xe2x80x9cfraction donexe2x80x9d output, suitable for rapid assembly and reuse of behavioral animation.
A system and method for declarative markup that allows temporal manipulation of media assets is presented. The media assets can be audio media, video media, animations, audio-visual media, images or events. Using the present invention a media sequence can be formed by playing more than one medium in series, in parallel or in any other temporal combination wherein a medium is cued to another medium. A media sequence created using the present invention can become part of a new media sequence, and the rate of playing the media sequence can be controlled by fields associated with the new media sequence. Also, using present invention, a media sequence can be cued to start playing at a fixed time before the end of a first media sequence, and in this instance the length of the first media sequence can be varied while still maintaining the fixed time from the end of the first media sequence.